How to process a single (point) XANES spectrum in GeoPIXE


You will need a XANES DA matrix (.damx) ready before you can do this procedure.

1. In the Sort EVT window, if you have not already analyzed any Maia data in your current session, load an image (.dai) file using the "From DAI" button. This is just to set up the Maia-specific parameters in the Sort EVT window.

2. In the Sort EVT window, switch from Image to EXAFS mode using the diamond buttons at the top of the window. Notice that the "First File" and "Last File" switch to "First Dir" and "Last Dir."

3. Click "First Dir" and navigate to your XANES raw data, then select the first Maia folder (select and highlight the folder, not the data within the folder) in the XANES scan folder (scan_00#, etc). To save space, GeoPIXE shows folder listed in groups like "14767...14771". Click on the first one of these to show all the folders listed, and choose the first folder. When you have the first folder highlighted, click Open.
  • Answer no to the question about using detector calibration parameters
  • Answer yes to the question about using Pileup and Throttle files
4. Click "Last Dir" and navigate to the last folder in your raw directory that corresponds to the XANES scan you want to analyze. Click Open.

5. Set the Output path to the appropriate folder in your analysis directory. Make sure the output filename is a ".xanes.csv" file- don't delete the ".xanes" part of the file extension!

6. You don't need to change anything in the Device or Scan tabs.

7. In the Flux tab, make sure that the IC Scaler channel, Preamp sensitivity, Preamp scale units, Dwell time, and Conversion (Q/IC) are all correct.

8. In the DA/E.Cal tab, click "Get" and then navigate to your energy calibration spectrum (.spec file) in your setup folder. Most likely this is a spectrum that was generated from the foil data. (e.g. Ti-Fe-foil-E-cal.spec or something similar). Select and highlight it and click Open.

9. In the DA/E.Cal tab, click "File" under "Dynamic Analysis (DA)" and navigate to your XANES DA matrix. Select and highlight it and click Open.

10. Turn on the cluster if desired, then click Start.
  • When you click Start, another window may pop up asking you to select the source list mode data. Make sure GeoPIXE is pointing to your first raw data folder, and click Open, just like in step 3. Repeat for the next pop-up asking for the final data, just like in step 4.
11. When the processing is finished, you will have a ".xanes.csv" file in your analysis folder that can be examined in LibreOffice, Excel, etc.

12. To see the spectrum, plot the Energy column versus the column that corresponds to your XANES element of interest.

-- LouisaSmieska - 13 Jun 2016

This topic: CHESS/Maia > WebHome > GeoPIXE > HowToGeoPIXEXANESSpectrum
Topic revision: 13 Jun 2016, LouisaSmieska
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